애프터마켓 모딩 및 튜닝과 관련하여 대부분의 애호가들은 대체로 자동차가 운반하는 무게의 양을 줄이는 것이 좋은 일이라는 데 동의합니다. 엔진이 밀고 당기는 무게가 줄어들면 마력이 더 효율적으로 사용되어 전반적인 성능이 향상됩니다. 또한 제동 거리가 짧아지고 조향 감각이 향상되며 전반적인 핸들링이 향상되고 연비가 향상됩니다.
여기에 작용하는 두 가지 유형의 체중 감소가 있습니다:스프링 중량과 스프링 중량. (차 중앙을 향하는) 쇼크 업소버부터 트렁크 뚜껑, 시트, 사람, 심지어 방향 지시등 손잡이에 매달려 있는 조그마한 공기 청정기까지 모든 것을 스프링 무게라고 생각하십시오. 스프링 하중량은 브레이크 로터, 브레이크 캘리퍼, 휠, 타이어 등 서스펜션 외부에 있는 모든 것입니다.
스프링 하중량을 줄이는 것과 관련하여 가장 쉬운 방법은 경량 애프터마켓 휠을 설치하는 것입니다. 다음은 몇 가지 상자를 선택하는 것입니다. 시그니처 모양을 제공하고 성능을 향상시켜 차량을 멋지게 꾸밉니다.
스프링 아래 무게가 스프링 무게 감소와 얼마나 같은지에 대해 모든 사람이 머리 속에 자신의 비율을 가지고 있는 것 같습니다. 포럼은 다양한 공식으로 가득 차 있습니다. 예를 들어, 어떤 사람들은 스프링 아래 무게 1파운드를 줄이는 것이 스프링 무게 10파운드를 줄이는 것과 같다고 생각합니다. 그러나 훨씬 더 많은 요인이 작용하기 때문에 이것이 반드시 사실은 아닙니다. 그러나 스프링 아래 무게를 줄이는 이점은 일반적으로 스프링 무게보다 더 분명합니다.
자동차의 성능, 연비 및 수명을 늘리기 위해 경량 휠 세트를 찾고 있다면 고려해야 할 몇 가지 사항이 있습니다. 추가된 모든 이점은 실제로 더 가벼운 휠을 장착했기 때문입니까, 아니면 다른 측면이 있습니까? 특정 경량 휠과 함께 제공되는 타이어가 귀하가 주로 하는 운전 유형과 장소에 가장 적합한 선택입니까? 자세히 살펴보겠습니다.
야금에 너무 깊이 들어가지 않고 일반적인 경험 법칙은 경량 애프터마켓 휠이 공장 OEM 휠보다 약하다는 것입니다. OEM 변종은 무게를 줄이는 데 큰 주의를 기울이지 않고 금속을 듬뿍 바르고 더 가벼운 휠을 만들기 위한 제조 공정도 더 비쌉니다. 자동차 제조업체는 다른 곳에서 연비와 가속/제동 성능을 개선하여 보다 비용 효율적으로 운영할 수 있습니다. 모든 휠에는 충족해야 할 특정 인증이 있으며 "가격, 품질 및 무게, 두 가지 선택"이라는 오래된 속담이 적용됩니다. 가볍고 품질 좋은 휠은 비싸고 OEM의 낮은 가격대로 제작된 무거운 휠은 저렴합니다.
다양한 휠 유형도 다르게 생산됩니다. 경량 휠을 만드는 데는 주조, 유동 성형 및 단조의 세 가지 공정이 있습니다. 주조는 가장 저렴하고 가장 일반적입니다. The process is to essentially pour hot liquid metal in a cast, let it cool, and the basis for a wheel is created. Flow-forming involves initially casting the wheel, but then reheating it back up and pulling out the barrel into the right size before its cooled back down. Forging is heating up and shaping a chunk of aluminum into a round block and then machining it into its final form. Flow-forming is generally more expensive than casting, and forging is the most expensive of the three.
All have their own benefits, but it's generally considered that flow-formed wheels are the best value, as they're not as expensive to produce as forged wheels and they’re lighter than cast wheels, though are still quite strong and can stand up to potholes, curbs on track, and other hard hits.
This leads us to a major consideration:What sort of driving will you be doing with your lightweight wheels? If they're bolted up full-time, know that they might not stand up to hazards as well as factory cast wheels. Personally, I've been lucky in my experiences rocking lightweight wheels all-year-round, on and off the track, but my experience is from having tires mounted up with at least a 50-series sidewall and about as much of a width as I can get away with on my old Mazda 2, thus giving the wheels plenty of sidewall to protect them.
I plan to swap lightweight wheels onto my current 2011 BMW 128i sometime in order to save around eight pounds per corner, or 32 pounds overall. Though, I'd be scared to mount up a tire that's near the minimum sidewall and width that the wheels can accommodate. Like I did with my Mazda 2, my BMW's lightweight wheels might be its primary set — why not reap performance benefits and better fuel economy in as many scenarios as I can and look good while doing it? Because of this, more rubber that's not stretched on there is a good thing.
When enthusiasts swap to lightweight wheels to achieve better grip and overall performance, usually stickier tires are on the docket as well. 왜 안 돼? Plus, the wheels are often wider than factory wheels, thus more of a contact patch with the road can be achieved. But will the weight difference really be there. Matching performance tires often weigh more due to having stiffer sidewalls and coming upsized over the factory size.
The best apples-to-apples comparison I can come up with is discussing my current setup and planning and how much weight I want to shed. Right now, my factory 17X7 BMW Style 256 wheels weigh just about 22.3 pounds each, coming out to 89.2 pounds total. The wheels I intend to swap for track use, D-Force LTW5s in 17X8, weigh 15.5 pounds each (62 pounds total), netting a 6.8-unsprung-pound loss at each corner, and 27.2 pounds total.
The tires that the previous owner upgraded to are 225/45/17 Yokohama Advan Apex V601s, which weigh 22.4 pounds each and have a treadwear rating of 280.
My Bimmer's current wheel and tire package comes to a grand total of 44.7 pounds per corner, and 178.4 pounds total. If I keep the same tires (though they won't be long for this world if I keep tracking on them), or replace them with a fresh set of the same brand/model/size, I'd truly experience a 27.2-pound weight loss.
If I decide to upgrade to stickier, 200-treadwear Falken Azenis RT660s in the same size with the D-Forces, the weight jumps up to 24.5 pounds per tire (40 pounds per wheel and tire). This doesn't sound like much, but it takes away from that 27.2-pound weight loss, netting just an 18.8-pound loss instead. That's still a hearty amount of shedding for unsprung weight. But imagine what even wider wheels and wider tires would mean?
Still, it wouldn't be for nothing. Despite not having much of a weight loss, any drop in unsprung weight is still better than a net weight gain, such as adding non-lightweight wheels and tires to your rig. Plus, the added benefits of more grip are quite apparent, as more grip means higher cornering speeds, more stability at speed, and shorter braking distances.
It should also be said that stickier tires will reduce fuel economy, as they have a tad more rolling resistance over conventional everyday street tires.
Another consideration is that the fitment of the aftermarket wheels must be taken into consideration. This is where following guides and reading Facebook groups and forums comes in handy. What sizes are popular for your particular car, especially among enthusiasts who use their cars the same way? Because I'm after more on-track grip and performance on a daily driver, it's in my best interest to see what setups fellow enthusiasts have successfully used.
In my case, there are some great guides out there for the E82 BMW 1 Series, including some by Bimmerworld and Apex Race Parts. Fitment Industries has some fields that can be customized to offer wheel and tire choices that will fit your particular setup and how much modification of the car's body you're up for doing.
How will changing the wheel's diameter, width, and offset affect how they fit in the wheel well and over the brake? In the E82 128's case, you can't fit as big of a wheel and tire package as other rear-wheel drive sports cars without adding more negative camber and modifying the fenders. It seems like a setup with a 17X8.5 wheel, 40 offset, and 245/40/17 tires is the limit without doing some fender rolling, but not without adding negative camber. This is related to the alignment and involves tilting the top of the tire more inward. Depending on suspension valving, doing some fender rolling might be required.
Personally, I'll probably go 225s or 235s, even with some added negative camber, so as to give myself more wiggle room against rubbing the tires on the inner fenders, contacting the shocks, and other issues.
There's more to all of this, but hopefully it's acted as some good pre-emptive food for thought, and at least put you in the mindset of figuring out what kind of net gains there are to experience. Plus, there's the financial aspect:What is your budget for wheels and tires, and what wheel and tire combo best fits it? Is it worth upgrading to x for y less pounds, at z more of a cost?
Hell, if you're after more grip on track for cheaper, why not keep the tough (albeit heavy) factory wheels, and mount up slightly narrower yet much stickier tires? There could be a net weight loss, and the more track-centric rubber will bode better for grip, as well as hold up to the higher heat and G forces.
There's also the aspect of the wheel and tire size altering the drivetrain's gearing, in which case I'd say refer to what fellow enthusiasts who've run bigger wheels and tires have experienced. When I ran 15X7.5 wheels with 205/50/15 tires on my Mazda 2, which originally came with 15X6 wheels and 185/55/15 tires (puny, right?), the speedometer read a little higher than the stock factory size.
Regardless of all of the above, it's fun researching all of this in the name of gaining more performance, potentially more fuel economy, and doing something that's a bit different than the way our vehicles were set up as everybody-friendly near-appliances.
